Method of wiping a curved surface



April 27, 1965 F. A. KROHM 3,180,753

METHOD OF WIPING A CURVED SURFACE Original Filed Oct. 19, 1955 '7Sheets-Sheet 1 INVENTOR. FRED A. KROHM BY NPJM I W w m a/Z'Z ZNM W4ATlQELNEYS April 27, 1965 F. A. KROHM METHOD OF WIPING A CURVED SURFACE7 Sheets-Sheet 2 Original Filed Oct. 19, 1955 INVENTOR.

FRED AKROHM 0611 IIQ NEY F. A. KROHM METHOD OF WIPING A CURVED SURFACEApril 27, 1965 7 Sheets-Sheet 3 Original Filed' Oct. 19, 1955 INVENTOR.FRED A KROHM ..w%

ATTORNEYS F. A. KROHM METHOD OF WIPING A CURVED SURFACE April 27, 1965'7 Sheets-Sheet 4 Original Filed Oct. 19, 1955 INVENTOR. FRED A. KROHM 4A J. ATTOBNEYS April 27, 1965 F. A. KROHM 3,180,753

METHOD OF WIPING A CURVED SURFACE Original Filed Oct. 19, 1955 7Sheets-Sheet 5 INVENTOR. FRED A. KROHM April 27, 1965 F- A. KROHM METHODOF WIPING A CURVED SURFACE 7 Sheets-Sheet 6 Original Filed Oct. 19, 1955April 27, 1965 F. A. KROHM 3,180,758

METHOD OF WIPING A CURVED SURFACE Original Filed Oct. 19, 19 55 7Sheets-Sheet 7 INVENTOR. FRED A. KROHM AZ/Q Z4 AT ORNEYS United StatesPatent 16 Claims. (Cl. 134-6) The present invention relates to a methodof wiping a curved surface and, more particularly, to a method of wipingthe outer surface of an irregularly curved windshield.

This application is a continuation of my application Serial No. 541,491,filed October 19, 1955, which was in turn a continuation-in-part of myapplication Serial No. 424,647, filed April 21, 1954, both applicationsnoW being abandoned.

For many years, the cleaning or wiping of an automobile windshield was amore simple matter than met today in that the surface of the windshieldwas flat. The method of wiping such a flat surface consisted primarilyof oscillating an arm about one end and scrubbing a wiping blade,attached to the other end of the arm,

through an arcuate path across the flat windshield surface. Althoughimportant developments in this art have taken place in improvedconstruction of arms, blades, and connectors therefor, the method ofoperating wiper assemblies across a windshield surface has remained inactual practice substantially the same.

Within recent years, automobile manufacturers have introduced curvedWindshields. Initially, the lateral curvature was slight and servedprimarily to eliminate the windshield center post. More recently, thecurvature has become greater, and in addition severely curved orsweptback end sections have been employed, giving rise to the expressionwrap-around Windshields since the curvature of theend sections issubstantially in a horizontal plane or direction.

Prior methods of wiping a windshield embodying an arm and a blade of atype previously mentioned are completely unsuited for effectively Wipinga severely and irregularly curved windshield. Many defects result. Forone, the wiper blade alone cannot conform to or accommodate the extremecurvature of the windshield at its swept-back lateral edges, andsections of the wiper blade actually leave the windshield surface,thereby affording no wipe at all at the edges of the windshield.Additionally, even those sections which remain in contact with thesurface may cease to provide an effective wiping action. For example, aneffective wipe is obtained when the wiping element, such as a rubberblade, provides what is termed in the art as a squeegee action. Theblade wiping edge must be substantially normal or erect to thewindshield surface to adequately wipe the surface. In wiping appreciablycurved Windshields by prior methods, the blade wiping edge does not liesubstantially erect to the Windshield surface and the proper squeegeeaction is not obtained, particularly as the wiper blade traverses themore severely curved end sections.

Another disadvantage of using prior methods to wipe present-dayWindshields is that chatter and actual scratching of the glass surfacemay result. Again, these shortcomings particularly appear at thelaterally curved end or wrap-around section where the surface recedesfrom the pivot axis of the arm so rapidly. The wiping attitude of theblade to the glass is so incorrect that chatter follows. Additionally,the metal holder for the wiping blade may actually contact the surfaceand scratch it during movement thereacross, as the blade fails to remainerect with respect to the surface.

In contrast to the foregoing, the present method effec- "ice tivelywipes a curved windshield and especially those of the wrap-around type.It has been discovered that in order to obtain an effective wipingaction across an irregularly curved windshield with an arm and a blade,the relation between these two parts must be an almost constantlychanging one for at least part of the travel of the blade. To provide aneffective Wipe pattern throughout a maximum surface area of thewindshield, the present method contemplates substantially three primaryand distinct steps in each of which the relation between the arm andblade is different.

For example, in one form of the method, arbitrarily starting with thearm and blade in the parking position, the first step comprises pivotingthe arm to move the blade across a windshield surface in an arcuate pathand toward an end section to a position of substantial parallelism withthe vertical elements of the surface. During this movement, the anglebetween the axes of the arm and blade can be substantially constant. Inthe second step, the blade is maintained in substantial parallelism withthe vertical elements of the surface to continue an effective wipe. Inthis area, the angular relation between the blade and the arm must beconstantly changing to realize this positioning of the blade. In thethird step, the blade is tilted in the direction of its movement. Thismaintains the blade erect against the surface and is particularlyeffective on a horizontally curved end section or on those windshieldshaving a wrap-around end section. Steps two and three can be performedsimultaneously, if desired.

When the windshield surface is curved in a transverse direction, thepresent method may also include a step of resiliently flexing the outerends of the wiper blade away from the arm to present a concave wipingsurface. This enables the blade to conform readily with the curvature ofany area traversed regardless of its direction of curvature.

It is, therefore, a primary object of the present invention to provide amethod of cleaning a surface of irregular curvature.

Another object is to provide a method of wiping a windshield surfacehaving lateral marginal portions of appreciable curvature.

A further object is to provide a method of wiping a windshield surfacewith an arm and blade wherein the angular relation between the arm andthe blade is varied to maintain the blade in full longitudinal contactand in proper wiping attitude with respect to the windshield surface.

A still further object is to provide a method of wiping a wrap-aroundwindshield surface with an arm and blade wherein the angular relationbetween the arm and blade is changed, and the blade is tilted withrespect to the arm simultaneously with the change in angular relation.

Yet another object of the invention is to provide a method of wiping awrap-around windshield surface with an arm and blade by supplying thearm with superposed parts having overlying offset portions and pivotingthe parts relatively to each other about an axis passing through theoffset portions to change the angular relation between the arm and bladeand tilt the blade with respect to the arm and maintain it substantiallyerect against the windshield surface.

Other objects are apparent from the following description of theinvention and the appended drawings.

On the drawings:

FIGURE 1 is a front view of a curved windshield equipped with a wiperassembly and diagrammatically illustrates some of the positions,designated A through E, which the arm and blade of the assembly may takein vtgping the surface in accordance with the present meth- 0 FIGURE 2is a sectional view taken along the plane IIII of FIGURE 1;

FIGURE 3 is a plan View, with parts broken away and in section, ofthewiper arm of FIGURE 2;

FIGURE 4 is an enlarged side view, partially in section, of the innerend of the arm of FIGURE 3;

FIGURE 5 is an enlarged longitudinal vertical section taken along theplane VV of FIGURE 3;

FIGURE 6 is a section of FIGURE 5 on the plane VI-VI and is taken in adirection normal to the plane of the drawing to illustrate a preset tiltof the wiping element with respect to the arm;

FIGURE 7 is an enlarged fragmentary view of the arm and blade inposition B of FIGURE 1;

FIGURE 8 is a section of FIGURE 7 along the plane VIII-VIII;

FIGURE 9 is an enlarged fragmentary view of the arm and blade inposition C of FIGURE 1;

FIGURE 10 is a section of FIGURE 9 along the plane X.X;

' blade.

FIGURE 11 is an enlarged fragmentary View of the arm and blade inposition D of FIGURE 1;

FIGURE 12 is a section of FIGURE 11 along the plane XII-XII;

FIGURE 13 is an enlarged fragmentary view of the arm and blade inposition E of FIGURE 1; and

FIGURE 14 is a section of FIGURE 13 along the plane XIVXIV.

As shown on the drawings:

FIGURES 2 through 6 illustrate one form of the apparatus which may beused in practicing the present method, and FIGURES 1 and 7 through 14show various stations or positions which the apparatus may take on acurved windshield in practicing the method.

Considering the apparatus first, the wiper assembly is carried by adrive shaft mounted in a support generally shown at It (FIGURE 4) bywhich the arm is also oscillated, the arm itself being generallyindicated at 11, and the wiping element or blade generally shown at 12.

The support 10 includes an annular boss 13-which ex' tends upwardly, asfrom the cowl of an automobile, and journals the drive shaft 14 having atapered spline section 15 and a threaded end section 16. A plate 17having an opening to pass the shaft 14 fits over the boss 13 and is heldin fixed relation thereto by a nut 18 engaging a threaded sleeve 19which is integral with and extends from the boss 13; A split Wire ring20 engages a circumferential groove in the shaft 14 and rests againstthe end of the sleeve 19 to prevent the shaft 14 from falling back. Theshaft 14 is oscillated by known means.

The arm 11 consists of an inverted U-shaped channel 21 having sides 23and having a bottom 22 suitably fixed to the sides. Adjacent theoscillated end of the arm (FIGURE 4), a pair of flanges 24 are pivotallyconnected to the sides 23 and are joined together by an integral plate25 having an opening to pass the shaft 14. A spring (notshown) connectsplate 25'to the channel to urge the arm 11 to pivot clockwise about theflanges 24 as viewed in FIGURE 4. An inverted cup 26 is fixed to theplate 25 and similarly has an opening to pass the shaft 14.

The cup houses a clutch disc 27 having serrated outer edges. A nut 28 isthreaded onto the threaded section 16 of the shaft to force the clutchdisc 27 into tight engagement with the tapered spline section 15 and thewalls of the cup 26 to hold the parts in assembled relation. A cover 29has wings 3t) pivoted to the opposite sides 23. of the channel. In alowered position, illustrated in FIG- URE 4, the cover conceals thestructure which connects the arm 11 to the shaft 14.

The forward end of the arm 11 is enlarged to form a housing 31 (FIGURE5) having an opening 32 on the underside thereof. The housing containstwo cooperating members which, by reason of their structures andrelative movement, induce the desired changes in the relation shipbetween the arm and they wiping element or i One member 33 extendsacrossthe housing 31 and is fixed to the bottom 22 of the arm, as byrivets 33b. Member 33 has a downwardly bent or offset forward orterminal section 33a and a slot 34 which extends longitudinally .of thearm for part of the length of the member and then slants to one side, asshown in FIG- URE 3, and as indicated at 34a. 7

The second member. 35 underlies the first member 33 and similarly has adownwardly bent orotfset section 35a which is pivotally fixed to section33a by a rivet 36. The axis of this rivet about which the members 33*and 35 turn makes an acute angle'with'the longitudinal axes of both thearm 11 and the wiping element 12, as more fully described hereinafter;Member 35' also has a slot 37 whichextends longitudinally of the arm 11for part of thelength of member 35*and then: slants to oneside as at-3.7a, the slot'portions 34a and 37a being oppositely directed (FIGURE3).

- U-shaped connector 42 to the offset sections 33a and 351:.

A pin 43 pivotally joins the legs of the connector to upturned sides ofa channel piece 44 which is riveted to the superstructure of the wipingelement 12, as shown in FIGURE 6. The wiping element is free. to turnabout 7 its length. Such an angle. throughwhich the wiping element mayturn around pin 43is illustrated in W in FIG- URE 5. A plane parallel tothe legs of the connector 42 has a preset angular relation with a planepassing through a longitudinal axis of the arm 11 and perpendicular tothe bight of the channel 21, so that the wiping element is placedat anangle X, as shown in FIGURE 7, with respect to this last-mentionedplane'even when the follower 38 is at the most outward point within theslots 34 and 37 and the members 33 and .35 are positioned as shown inFIGURE 3, that is, prior to any relative movement therebetween.

The wiping element 12 may be of the type illustrated in US. Patent No.2,596,063 toJohn W. Anderson. A primary bridge or pressure element 45(FIGURE 2) has its ends pivotally joined to secondary bridges orpressure elements 46 and 47. The latter carry a rubber blade 48 having areinforcing strip or flexor 49. This structure is particularly useful inpracticing the present method when it is desired to include a step offlexing the outer ends of the wiping blade or element away from the arm11 to present a concave wiping surface along the length of the blade 48,because the bridges enable the blade readily to assume this flexedposition.

Operation Considering now the use of the apparatus just described inpracticing the present method, FIGURE 1 illustrates five arbitrarilychosen positions which. the arm 11 and Wiping element 12 may take intraversing a curved windshield S. Even though the windshield may curvein a longitudinalhorizontal direction, it may be considered as composedof an infinite number of straight lines or vertical elements L placedside by side as is understood in the art. Element lines may be definedasstraight lines drawn from and joining points at the intersection ofthe roof panel and windshield with corresponding points on the cowlsection of an automobile. It will be noted that at the relatively flatcentral portions of the windshield, the element lines are substantiallyparallel, and, at the corner section of greater curvature, the lines arenonparallel and coverage upwardly. Thus, the central portions may befiat or have a relatively large radius of curvature in a transversedirection of the windshield, while the corner section has a relativelysmall radius of curvature in the same direction.

Beginning with position A, which represents the most inward station ofthe arm and blade, the arm 11 pivots clockwise'as viewed in FIGURE 1 tomove the wiping element in a substantially widthwise direction acrossthe windshield surface S through an arcuate path and toward a laterallyor transversely curved end section S until position B is reached(FIGURES 1, 7, and 8). During this movement there need be no change inthe angular relation between the longitudinal axes of the arm and thewiping element or blade. I11 the same manner, the preset tilt of thewiping element which defines the angle X with a plane passing through alongitudinal axis and perpendicular to the arm 11 may also remain thesame while the wiping element moves from position A to position B. Asthe arm 11 continues to move, the wiping element passes from position Bto position C (FIGURES l, 9, and Because the end of the rod 39 is joinedto the fixed plate 17 and this continued movement places the housing 31farther from the pin position connection 17a, the follower 38 is pulledinwardly along the slots 34 and 37. Position C is chosen, since at thispoint the follower 38 reaches a point where these slots just begin todiverge and, therefore, there is still no relative movement between themembers 33 and 35. Accordingly, the angle X between the longitudinalaxes of the arm and wiping element or blade and the angle X between aplane passing through a longitudinal axis and perpendicular to thewiping element and a plane similarly passing through the longitudinalaxis of the arm have not as yet changed.

However, when arm Ill passes from position C to position D (FIGURES 1,11, and 12), the wiping element is placed in substantial parallelismwith the vertical element lines L and remains substantially sothroughout the remainder of the wiping stroke. To accomplish this, therelationship between the arm and the wiping element must be changed. Asthe arm continues to rotate, the follower 38 is pulled into thediverging portions 34a and 37a of the slots 34 and 37, forcing member 35to pivot about the rivet 36: This produces two important changes. Forone, the angle between the longitudinal axes of the arm and wipingelement is increased to an angle Y to maintain the wiping element insuch substantial parallelism. For the other, as member 35 pivots aboutmember 33, the bent or offset sections 33a and 35a pass over one anotherand because of their slanted configuration,

force the wiping element further to one side. That is, the wipingelement is tilted in the direction of its movement to define a new angleY between a plane passing perpendicularly through the wiping element anda plane similarly intersecting the arm 11. As shown in FIGURE 12, thismaintains the blade 48 substantially erect against the surface S toprovide the desired squeegee action and prevent scratching of thesurface by a metal part of the wiper assembly.

In passing from position D to position E (FIGURES 1, l3, and 14), theaction just described is continued and becomes more important as themore severely curved end section S is traversed. Thus, a still largerangle Z is formed between the longitudinal axes of the arm and wipingelement, and a larger angle Z is defined between planes passingperpendicularly through the longitudinal axes of the arm and wipingelement with the same attendant advantages previously described. In theembodiment shown, the end portion of the blade 48 are also continuouslyflexed away from the arm 11 by reason of the previously mentioned bridgeconstruction which transmits an applied force from the arm to medialportions of the secondary bridges 46 and'47. This presents a concavewiping surface along the length of the blade 48 to conform with thecurvature of the areas traversed on the surface S.

Although in the embodiment shown and described, the changing of theangle between the longitudinal axes of performed simultaneously;Instead, these steps can be followed at different times, or they can beperformed simultaneously through only part of each step. The

. timing of these two steps of the invention can be controlled by thedesign of the two members 33 and 35 and particularly by spacing theiroffset end sections 33a and 35a so that the latter coact as desired.

It will now be apparent that the present invention provides an improvedmethod of wiping a curved surface, such as a Windshield of irregularcurvature. By

" altering the relationship between the longitudinal axes of an arm andwiping element as well as altering the relationship between planespassing perpendicularly through the arm and wiping element, the wipingelement is maintained erect against the surface and in substantialparallelism with the vertical elements thereof throughout a portion ofthe travel of the wiping element across such a surface. This provides aneffective squeegee type of wiping action which extends as well aroundthe curved end of a wrap-around windshield.

Various details of construction may be changed through a wide rangewithout departing from the principles of this invention, and it is,therefore, not the purpose to limit the patent granted hereon otherwisethan necessitated by the scope of the appended claims.

I claim:

1. A method of wiping the surface of a windshield having a first portionand a laterally curved second portion with an elongate wiping elementcarried by an osci1- latable wiper arm comprising: moving the wipingelement through the agency of the arm across the surface of the firstportion onto the curved second portion, maintaining the wiping elementin a substantially normal position with respect to the surface of thefirst portion during such movement, and then tilting the wipingelem'entabout an axis parallel to its longitudinal axis in a direction 10f itsmovement and relative to the arm to maintain the wiping element in asubstantially normal wiping position asthe wiping element passes overthe curved section;

2. A method of wiping a surface having'a curved end portion with anelongate wiping element carried by an arm, comprising: moving theelement through the agency of the arm over part of the surface in asubstantially widthwise direction through an arcuate path and toward thecurved end portion, continuing to move the element toward and onto thecurved end portion While maintaining the element in a substantiallyperpendicular position with respect to its direction of movement, andthen tilting the element forwardly in the direction of its movement andrelative to the arm to maintain the element in a normal wiping positionwhile it is moved on said end portion.

3. A method of wiping the outer surface of a windshield having a curvedend portion with an oscillatable arm carrying a wiping blade adjacentone end, comprising: moving the arm to move the blade across the outersurface from a position adjacent the center of the Windshield through anarcuate path and toward the curved end portion to a positionsubstantially perpendicular to its direction of movement, continuing tooscillate the arm to move the blade toward and onto the curved endportion while simultaneously altering the angle between the longitudinalaxes of the arm and blade, and tilting the blade about its longitudinalaxis and with respect to the arm while moving the blade onto and throughsaid curved end Portion to hold the blade substantially erect againstthe curved end portion of the windshield surface.

4. A method of wiping the outer surface of a wind shield having ahorizontally curved end section, a curved frontal section adjacenttheend section, with an oscillatable arm provided with a wiping bladeadjacent one end, comprising: oscillating the blade through an arcuatepath on the frontal section and onto the curved end section whilesimultaneously altering the angle between the longitudinal axes of thearm and blade and concomitantly with said altering of the angle tiltingthe blade about its longitudinal axis relative to the axis of the arm inthe direction of its movement to hold the blade in a substantiallynormal position against the windshield surface,

and at all times flexing the end portions of the blade away i bladeadjacent the other end is used to effect the wiping,

the steps of altering the relationship between longitudinal axes of thearm and blade and the position of the blade about an axis parallel toits longitudinal axis to maintain the blade erect against the outersurface regardless of the curvature of the area traversed, whichinclude: pivoting the arm to move the blade substantially in a widthwisedirection across the medial section of the windshield to place the bladein a position substantially perpendicular to its direction of movementwhile holding the angle between the longitudinal axes of the arm andblade substantially constant, continuing to pivot the arm to move theblade toward the curved end section and simultan ously changing theangle between the arm and blade to maintain the blade in saidsubstantially perpendicular position, pivoting the blade about an axissubstantially parallel to its longitudinal axis in at least onedirection of its movement while moving the blade onto and across saidcurved end portion to hold the blade in a substantially normal positionagainst the outer surface of said curved end portion, reversing themovement of the arm and blade toreturn the blade to its starting pointwhile performing the foregoing steps in reverse order.

6. The method of moving and controlling a Windshield wiper blade on awiper arm for movement with respect to the surface of a windshield,which consists in pivoting the blade to vary the angularity of itslongitudinal axis with respect to the longitudinal axis of the arm andsimultaneously forcibly tilting the blade'aoout its longitudinal axisand with respect to the arm to substantially maintain the blade in anormal position to the surface as the arm is moved in a substantiallyarcuate path across a portion of a Windshield.

7. In a method of wiping a windshield of irregular curvature and havinga marginal portion of appreciable curvature by the use of a reciprocablearm carrying a wiping blade, the steps of reciprocating the arm to movethe blade in a substantially arcuate path across the windshield andtoward said marginal portion, maintaining the longitudinal axes of thearm and blade in substantially the same angular relation as long as theblade remains in effective wiping relation with respect to thewindshield, then altering the angle between the longitudinal axes of thearm and blade to retain said effective wiping relation, and tilting theblade about an axis parallel its longitudinal axis relative to the armin at least one direction of its movement as the marginal portion isapproached and traversed to hold the blade substantially normal againstsaid marginal portion.

8. In a method of wiping a windshield having irregular curvature and amarginal portion of appreciable curvature with a reciprocable armprovided with a wiping blade adjacent one end and means to pivot theblade with respect to the arm to alter the angle between thelongitudinal axes of the arm and blade, the steps of providing a periodof lost motion for said pivoting means, pivoting the 'arm at itsopposite end to move the; blade in a substantially arcuate path acrossthe windshield and toward said marg'mal'pontion and effecta squeegeewipe, actuating said pivoting means and maintaining the longitudinalaxes" of the arm and blade in substantially the same angular relation bymeans of said lost motion period, continuing to pivot the arm andarcuate thc'pivoting means to increase the angle between thelongitudinal axes of the arm and blade as the pivoting means begins aneffective pivoting action and tomaintain the squeegee wipe across theirregularly curved windshield, and tilting the blade about an axisparallel to its longtudinal axis relative to the arm as the marginalportion is approached and traversed to hold the blade substantiallynormal against said marginal portion.

9. In a method of wiping a windshield surlace of variant curvature bythe use of an oscillatable arm, carrying a windshield wiper blade, thesteps of interconnecting the arm and the blade for relative movementabout an axis lying in the longitudinal verticalplane of the arm andinclined at an acute angle with respect to the axis of the arm, andtraversing said arm and blade in a direction widthwise of the bladeacross the surface of the windshield and effecting relativemovementtherebetween about said axis to vary the angular relationship betweenthe axes of the armand the blade intwo directions to conform the edge ofthe blade to the windshield surface and to retain the edge of the bladesubstantially normal to said surface.

10. A method of wiping, with an elongate wiping element carried by anarm, a surface having a recedingly curved end portion, comprising:moving the element by the arm overa part of the surface in the directionof the end portion through a generally arcuate path, pivoting theelement with respect to the arm while continuing to move it toward andonto the end portion and tilting the element about an axis parallel toits longitudinal axis in the direction of its movement to maintain itsubstantially normal to the surface while it is moved across said endportion.

11. The method of Wiping a surface with a blade which comprises anelongate support and a wiping element and which is carried by a wiperarm, which consists in moving the arm and blade so the blade will travelsubstantially widthwise on the surface and tilting the blade about itslongitudinal axis relative to the arm for at least some distance duringsuch travel to substantially maintain the blade normal to such surface.

12. The method of wiping a curved surface with a blade which isresiliently flexible in a plane substantially perpendicular to thesurface and which is pivotally carried by an arm, which consists indirecting the arm so the blade travels substantially widthwise on thesurface and tilting the blade about its longitudinal axis relative tothe arm to maintain the blade normally erect with respect to saidsurface during suchtravel.

13. The method of wiping a curved surface with a blade which isresiliently flexible in a plane relatively perpendicular to the surfaceand which is carried by an arm, which consists in directing the armsothe blade travels substantially widthwise on the surface, and forciblytilting and pivoting the blade relative to the arm to. maintain theblade in a normal condition so it will readily conform to the surfaceduring such travel.

14. The method of controlling an elongate windshield wiper bladerelative to an elonagte wiper arm which consists in pivoting the bladecrossways with respect to the longitudinal axis of the arm, tipping thelongitudinal axis of the blade relative to a plane containing thelongitudinal axis of the arm, and tilting the blade about an axisparallel to its longitudinal axis through a portion of an arcuate pathof movement of the blade and arm.

15. The method of wiping a surface comprising the steps of moving thearm and blade about an axis so that the blade travels substantiallywidthwise on the surface, pivoting the blade crossways of the arm duringa portion of its path of travel, and simultaneously tilting the bladeabout an axis parallel to its longitudinal axis with respect to the armduring the same portion of its path of travel.

16. The method of wiping the surface of a curved windshield having afrontal portion and a lateral portion wherein the lateral portion ismore severely curved than the frontal portion comprising the steps of:oscillating an arm and a blade across the portions of the windshieldwith the Wiper in contact therewith and wherein the wiper is carried bythe arm about a fixed axis disposed at an oblique angle with respect tothe axis of the arm and lying in a vertical plane on the arm,maintaining the blade in a wiping position normal to the surface of thefrontal portion as the blade passes thereover, maintaining the blade ina wiping position normal to the surface of a lateral portion as theblade passes thereover by pivoting said wiper about said fixed obliqueaxis and thereby tilting saidhlade about an axis generally parallel tothe long-itudinal axis of the blade and relative to the arm.

Reterences Cited by the Examiner UNITED STATES PATENTS 3,324,365 7/43Coutts 15250.4 2,356,424 8/44 Paton 15-25023 2,500,010 3/50 Schoon15-25009 2,596,063 5/42 Anderson 15250.42 2,691,186 10/54 Oishei et al.15'250.21 2,309,388 10/57 Vv'ise 15-25023 2,979,425 4/61 Krohrn 134-63,006,788 10/61 Krohm 134-6 FOREIGN PATENTS 1,047,648 7/53 France.

CHARLES A. WILLMUTH, Primary Examiner.

UNITED STATES PATENT ()FFICE CERTIFICATE OF CORRECTION Patent No.3,180,758 April 27, 1965 Fred A. Krohm It is hereby certified that errorappears in the above numbered patent requiring correction and that thesaid Letters Patent should read as corrected below.

Column 3, lines 74 and 75, for "relation ship" read relationship column4, line 73, for "coverage" read converge column 5, line 21, strike out"position"; line 37, strike out "the", second occurrence; line 41, for"rivet 36:" read rivet 36. line 66, for "portion" read portions Signedand sealed this 28th day of September 1965.

(SEAL) Auest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

11. THE METHOD OF WIPING A SURFACE WITH A BLADE WHICH COMPRISES ANELONGATE SUPPORT AND A WIPING ELEMENT AND WHICH IS CARRIED BY A WIPERARM, WHICH CONSISTS IN MOVING THE ARM AND BLADE SO THE BLADE WILL TRAVELSUBSTANTIALLY WIDTHWISE ON THE SURFACE AND TILTING THE BLADE ABOUT ITSLONGITUDINAL AXIS RELATIVE TO THE ARM FOR AT LEAST SOME DISTANCE DURINGSUCH TRAVEL TO SUBSTAANTIALLY MAINTAIN THE BLADE NORMAL TO SUCH SURFACE.